A. Protein Kinase C Project The universe of synthetic DAG-lactones designed as potent PKC ligands continues to expand with the objective of achieving full isozyme specificity. The major findings this year are: 1) The identification of two very effective DAG-lactones capable of maximally activating latent HIV-infected cells by activating HIV transcription via a PKC pathway while minimizing side effects of CD4 and CXCR4 downregulation and tumor necrosis factor alpha upregulation. Treatment with these DAG-lactones rendered cells sensitive to killing by anti-HIV immunotoxins. 2) The development of a solid-phase synthetic method that allows the simultaneous synthesis of 96-member libraries of unique compounds with the objective of exploring chemical diversity in the vicinity of the binding pocket of the C1a and C1b domains of the various isozymes. Several new candidates with unexpected activity have been discovered and their individual synthesis in large scale is underway. 3) The synthesis of the first DAG-lactone with a side chain in the form of a rigid rod constructed with alternating acetylene units and benzene rings was built. Variations in the length of the rod will explore the depth of membrane insertion. Biological testing in underway. B. DNA Methyl Transferase Project (Zebularine). The ability of zebularine [2(1H)-pyrimidinone riboside] to reactivate a silenced p16 gene and demethylate the promoter region in the T24 bladder carcinoma cell line in vitro as well as in tumors grown in BALB/c nu/nu mice was demonstrated. A DTP DDG meeting in October 20, 2003 will likely result in a recommendation to move zebularine into clinical trials. The LMC has embarked in a pro-drug approach to improve drug delivery.